Like the others have accuratly stated, you need to address the cause of the high temp in traffic.

262 is not critically overheated, especially since ( I hope) you have iron heads on the iron block. Where problems arise is when aluminum heads shift on an iron block, making a mess of head gaskets. But you will know more after you fire it back up after it cools. Hopefully, it will be fine. (I have 2 chevy trucks that will hit 250-260 on a long pull up a 6% grade in the summer with the A/C on. So far, no problems.